Noncarcinogenic risk assessment of ten heavy metals in nine freshwater species sourced from market-ready landing sites

Abstract

The public health risks associated with consumption of freshwater species potentially contaminated with metals at Otuocha, Ose and Atani landing sites in Anambra State, Nigeria were assessed. Species comprising seven fishes (Malapterurus electricus, Clarias gariepinus, Tilapia zillii, Gnathonemus tamandua, Citharinus citharus, Oreochromis niloticus and Auchenoglanis occidentalis) and two edible snails (Bulinus globosus and Bulinus africanus) were analysed for ten heavy metals with known varying degrees of toxicities: arsenic (As), cadmium (Cd), chromium (Cr), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), iron (Fe), copper (Cu) and zinc (Zn). Results showed that concentrations of As (4.76 mg kg−1), Cr (1.54 – 6.60 mg kg−1) and Hg (1.07 – 2.66 mg kg−1) were higher than the FAO/WHO safe limits. The calculated target hazard quotient and hazard index values, representing quantitative estimates of noncarcinogenic risk of dietary exposure from freshwater species consumption, were below 1 for all metals, which indicate that freshwater species pose no noncancer risk from oral exposure under the environmental conditions of the study. Further studies across spatiotemporal scale are recommended to understand impact of season–location variables on metal concentrations in those freshwater species examined.